1. Field of the invention
The present invention relates to an apparatus for processing a microelectronic device and in particular to an apparatus for degolding or applying tin solder on electrically conductive elements arranged on a face of the device.
2. Description of the related art
In solder processing of electronic parts it is known that pre-tinning before soldering is necessary and that fresh pre-tinning is preferable to the electro-deposition techniques.
In the processing of microelectronic devices such as chip carriers, it is known to remove gold and/or to tin the conductive elements on a device face by dipping said face in a solder melt. Several processes are known for removing excess of tin : shocks or soaking the device in oil, or spinning the device about an axis perpendicular to said face.
The solder melt is at medium temperature recommended by the process and standards (230.degree. C. as an example), and the solder material which is withdrawn by the device cools down rapidly after the separation. Accordingly, in order to achieve a solder deposit of regular thickness on the conductive elements, and to efficiently eliminate the molten solder remaining on the non-conductive portions of the device, it is desired to start the spinning operation as soon as possible after the conductive elements are separated from the melt, i.e. after the meniscus between the device face and the melt breaks. However, the level of the solder melt is not known accurately when a series of devices are processed successively because an amount of solder is withdrawn from the melt by each processed device, so that it is difficult to determine when the spinning operation should be started. It is possible to attach a level sensor to the device holder for detecting the melt level and controlling the spinning operation in response thereto. However the operation of such sensor implies specific signal transmission and processing means and delays the beginning of the spinning step.